Mate-attracting features such as the bright plumage of a male peacock is:

intersexual selection

Antibiotic resistance in bacteria is an example of what?

directional selection

Scientists have warned doctors of the danger of their increasing use of antibiotics for treating minor illnesses. They are concerned because:

strains of bacteria that are resistant to these drugs will become more widespread

Which genotype relative to the sickle-cell allele has the greatest reproductive success in regions where malaria is a common disease?

the heterozygous genotype

Under some conditions, heterozygotes have greater reproductive success than homozygotes. What is this called?

heterozygote advantage

Macroevolution can be defined as:

the appearance and extinction of species and the formation of major new branches on the tree of life

Lake Victoria is home to a group of related fishes known as cichlids. Hundreds of forms are present, differing slightly in their color patterns, habitat use, and feeding behavior. What is the best method for scientists to determine conclusively whether the fish are members of a population that has a lot of variation or members of entirely different species?

observing them together under natural conditions to see if they interbreed to produce fertile offspring

Speciation, or the formation of new species, is:

the bridge between microevolution and macroevolution

The ____ species concept is the most applicable to classifying species from the fossil record?

morphological

When a horse and a donkey mate, they produce infertile hybrids called mules. According to the ____ species concept, horses and donkeys are____

biological, different species

According to the biological species concept, a species is:

a group of populations whose members can interbreed in nature and produce fertile offspring

Often, the morphological species concept is used to define and describe species. Why?

this is the most convenient way of identifying species, and it is one of the few ways to identify fossil or asexual species

Two species of clams inhabit the same marine habitat along the Atlantic coast. One releases gametes into the water in early spring, and the second species releases gametes into the water in late summer. Which type of reproductive barrier is at work between these species?

temporal isolation

Three species of frogs all mate in the same ponds, but they pair off correctly because they have different calls. This is a specific example of a ____ barrier, called _____

prezygotic, behavioral isolation

Individuals of different species living in the same area may be prevented from interbreeding by responding to different mating dances. This is called:

behavioral isolation

Two rodent populations become separated when a large canyon develops in a previously unbroken forest. When is allopatric speciation between the two populations complete?

when the two populations evolve to be different enough so that they are incapable of interbreeding successfully when given the opportunity to do so under natural conditions, allopatric speciation is complete

What is the first step in allopatric speciation?

geographic isolation

Uplift and formation of a mountain range divides a freshwater snail species into two isolated populations. Erosion eventually lowers the mountain range and brings the two populations together again, but when they mate, the resulting hybrids all produce sterile young. This scenario is an example of:

allopatric speciation

In the mountains of the southeastern United States, there are may similar but distinct salamander species that are restricted to particular mountaintops or ridge systems. They are found in patches of suitable high-elevation habitat, separated by unsuitable lowland areas. This distribution pattern indicates:

numerous allopatric speciation events

Sympatric speciation typically occurs through ___ and through _____

polyploidy in plants, habitat differentiation in animals

Speciation without geographic isolation is called ___ speciation

sympatric

Sympatric speciation is:

the appearance of a new species in the same area as the parent population

Organisms that possess more than two complete sets of chromosomes are said to be:

polyploid

What do Dodd's experiments with fruit flies indicate?

reproductive barriers will arise most quickly if isolated populations experience and become adapted to differing environments

In a hybrid zone, ___ can occur if the reproductive barrier between two species is weak, as seen among cichilids in the murky waters of modern Lake Victoria.

fusion

Biologists have found more than 500 species of fruit flies on the various Hawaiian islands, all apparently descended from a single ancestor species. When this ancestor colonized the island chain, it found few competitors: many insect and fly families present in other regions are absent from the isolated Hawaiian islands. This example illustrates:

adaptive radiation

Earth probably formed ___ years ago, and the first life evolved as early as ____ years ago

4.5 billion, 3.9 billion

The "big bang" that produced the universe is thought to have occurred:

10 to 20 billion years ago

What is thought to have been the first step in the origin of life?

formation of organic monomers such as amino acids

Miller was the first to show that:

amino acids and other organic molecules could have been generated on a lifeless Earth

Protobionts are:

spheres with lipid membranes that concentrate solutes and can even carry out simple metabolic reactions if provided with enzymes

Hot sand, clay, or rock may have played an important role in the origin of life because:

evaporation of seawater from these surfaces could have concentrated monomers, leading to the formation of polymers through dehydration synthesis

A current leading hypothesis about the first system of inheritance in the earliest life forms involves:

self-replicating RNA molecules aided by ribozymes

The earliest cells were most likely:

prokaryotic

About 2.2 billion years ago, oxygen released by early ____ became fairly abundant in the atmosphere, enabling the evolution of _____

photosynthesis, cellular respiration

The technique called radiometric dating is based on:

the steady, clocklike decay of certain radioactive isotopes over time

The C14C12 ratio can be used to date fossils that are up to approximately how old?

75,000 years

If you want to see a dinosaur, it would be best to set the controls of your time machine for the:

Mesozoic era, 150 million years ago

The correct order of the geologic eras, from most ancient to most recent, is:

Precambrian, Paleozoic, Mesozoic, Cenozoic

Earth's continents and seafloors together form a thin outer layer of the planet called the:

crust

The Himalayas are an example of a mountain range formed as a result of:

the collision of two continental plates

The end-Cretaceous extinctions were followed by the:

adaptive radiation of mammals

Homeotic genes are responsible for:

determining the location and pattern of structural features such as limbs

Fish that were ancestral to the first amphibians may have had limbs that were used for moving through underwater vegetation, and were later adapted for use in walking on land. If so, the limbs were an example of:

an exaptation

The concept of ____ suggests that feathers originally evolved ____

exaptation, for some other function and only later became adapted for flight

Structures that evolved from the same structure in a common ancestor are:

homologous

The scientific study of the diversity of organisms and their evolutionary relationships is called:

systematics

Systematic biologists have used a wide variety of traits to reconstruct the phylogenies of particular groups of organisms. Which type of trait can also be analyzed to estimate the divergence times between taxa?

gene sequences

Members of what was once the kingdom Monera are now divided into two major domains called the: